Volume 1 Issue 8 June 1999.pdf

(2858 KB) Pobierz
9ROXPH ,VVXH
-XQH
Copyright © 1999 Wimborne Publishing Ltd and
Maxfield & Montrose Interactive Inc
EPE Online, Febuary 1999 - www.epemag.com - XXX
PROJECTS AND CIRCUITS
CLIPPING VIDEO FADER -
by Robert Penfold
The first in a new series of Starter Projects — add a simple fading facility to your
camcorder / TV link
574
578
581
588
601
INGENUITY UNLIMITED -
hosted by Alan Winstanley
Car Auxiliary Power Protection; Metal Detector Adaptor; Alarm Add-On
PC AUDIO FREQUENCY METER
-
by Robert Penfold
Use your PC’s bidirectional printer port to monitor frequencies up to 32KHz
Musical Sundial -
by John Becker
When the sun has got his hat off (hip-hip-hip-hooray) there’s no shadow
of doubt you’ll find fun with our musical garden gnomon!
PIC TOOLKIT MK2 Part 2 -
by John Becker
Concluding with detailed discussions of the many software options offered by
this sophisticated PIC ‘F87x and ‘x84 programmer
SERIES AND FEATURES
NEW TECHNOLOGY UPDATE -
by Ian Poole
Innovative encapsulation heralds even smaller IC packages
611
613
623
628
ALAN DOWER BLUMLEIN -
by Barrie Blake-Coleman
An unsung genius who greatly influenced the development of 20th century electronics
INTERFACE -
by Robert Penfold
Using Delphi to visually program your PC as a virtual meter
CIRCUIT SURGERY -
by Alan Winstanley and Ian Bell
More on Current Sources; Current Mirrors; Solder Joint Protection;
Etching and Electroplating
EDISON 3 REVIEW
- by Robert Penfold
Taking a close-up look at an upgraded circuit simulation and analysis program
633
638
648
PhizzyB COMPUTERS Part 8 - by Alvin Brown and Clive “Max” Maxfield
And now the (random) end is here, let us say (not in a shy way), they did in their way -
and you’ve been PhizzyBly moved by it, haven’t you!
NET WORK - THE INTERNET PAGE -
surfed by Alan Winstanley
Melissa’s Mayhem; Cool Talk; Updates
REGULARS AND SERVICES
EDITORIAL
NEWS
-
Barry Fox
highlights technology’s leading edge. Plus everyday
news from the world of electronics.
addresses general points arising.
The essential guide to component buying
572
650
655
653
READOUT
-
John Becker
for
EPE Online
projects.
SHOPTALK -
with David Barrington
Copyright © 1999 Wimborne Publishing Ltd and
Maxfield & Montrose Interactive Inc
EPE Online, June 1999 --www.epemag.com --XXX
EPE Online, June 1999 www.epemag.com 571
POINTLESS PROJECT
Sometimes a project comes along that catches the imagination of many readers, and we expect our
Musical Sundial
to do just that. In fact we expected to publish this project several months ago, but the
author lives in the UK, and it took longer than expected for him to enjoy enough sunny days to fully test
the device.
What a wonderful use of microelectronics to do something which can easily be done with a stick in the
ground and no moving parts
unless you count the sun! Of course, our project equally has no moving
parts (unless you count billions of electrons!).
When we first heard about this idea, our initial thoughts were what a wonderfully fascinating project.
At no time has anyone questioned our decision to publish it on the grounds that it is a pretty pointless
exercise. It's fun, it's fascinating and it's a real conversation piece
we bet it gets people talking at your
next barbecue.
Suffice to say that everyone we have talked to about it is fascinated and wants to know more. Let us
know if you feel the same or if the pointlessness of it makes you angry.
BRITISH GENIUS
Readers of the printed edition of
EPE
will know something of Alan Dower Blumlein, but probably not
a lot. Barry Fox has previously commented on his life and the problems with one individual hoarding
archive material that had been collected to write a biography. I'm pleased to say that this issue carries a
feature on Blumlein's life; he played a very important part in the development of electronics in the
twenties to early forties and it is right that his name should be up there with Bell, Baird, Edison and others.
We’re also pleased to note that what is reported to be an excellent book on Blumlein's life is about to be
published
more details in the article.
It is sad that such an outstanding British engineer has, for various reasons, not received the
acknowledgement he deserves and we are very pleased to be able to do our bit to put this right. Blumlein
made significant contributions in a wide range of electronic disciplines and had a great impact on the
development of radar, television, and stereo recording amongst other things.
Copyright © 1999 Wimborne Publishing Ltd and
Maxfield & Montrose Interactive Inc
EPE Online, June 1999 www.epemag.com 572
EPE Online, June 1999 - -www.epemag.com - -XXX
EPE MOOD PICKER
One of the more unusual projects published in the printed edition of
EPE
last year was
the EPE Mood
Changer
which was featured in the June '98 issue. This generated a weak magnetic field at an adjustable low
frequency. Such fields are thought to encourage electrical activity of similar frequency in the brain, which in
turn may promote associated moods and sensations such as deep relaxation, creativity or even sleep.
Although a commercial device of this kind was on sale at a fairly high price, at the time of publication we
had no idea whether this notion was valid so the aim was to let readers try it out at minimal cost. Feedback
received since then has been most encouraging however, especially from insomnia sufferers, so this im-
proved design should receive a warm welcome.
The frequency range generated is from 1 5Hz to just under 22Hz and this can provide
¬
Alpha:
Deep Relaxation, Meditation, Stress Relief
Delta:
Deep Sleep
Beta:
Normal Consciousness, Optimism
Theta:
Creativity, Dreaming
One of the available switched frequencies is at the “Schumann Resonance”. This intriguing phenomenon
is one of the naturally occurring magnetic fields that have always surrounded us. It appears that the space be-
tween the earth's surface and the ionosphere forms a gigantic resonant cavity with physical dimensions that
give it a frequency somewhere between 7Hz and 8Hz. Excitation by phenomena such as lightning starts oscil-
lation, and very low attenuation at these frequencies allows it to keep going more or less continually.
Enthusiasts of the effects of fields at this frequency say that modern man is missing out on its supposed
beneficial effects because it tends to be masked by more powerful fields from the electrical equipment and
wiring which nowadays surrounds us all. There is even a story that NASA installed Schumann frequency field
generators in spacecraft after finding that space sickness was in part due to the astronauts travelling beyond
the range of this field.
NEW SERIES
OSCILLATORS
Most text books deal with oscillators in a theoretical way. This series, prepared with the electronics enthu-
siast and experimenter very much in mind, is intensely practical. Tried and tested circuits are fleshed out with
component values, and their vices and virtues are exposed.
Part 1: Introduction; the Hartley oscillator and its variants.
Part 2: Buffer amplifiers; the Colpitts oscillator and its variants.
Part 3: “Two-terminal” LC oscillators; the Armstrong and Meissner oscillators.
Part 4: Crystal controlled oscillators; variable frequency crystal oscillators; frequency multipliers.
Part 5: Sinusoidal RC oscillators; relaxation oscillators; IC and discrete transistor based circuits.
LED STROBOSCOPE
The scientific purpose of a stroboscope is to “freeze” moving machinery. The basic idea is to synchronize
the flashing light of the stroboscope with the machine so that the light flashes at precisely the same points in
each cycle of the machine. The flash of light must be much brighter than the ambient light level so that any
onlookers only see the machine during the pulses of light. Because observers only see the machine at the
same point in each cycle it seems to be stationary.
The use of LEDs in this design keeps the cost to a minimum, enables an extremely simple circuit to be
used, and permits safe operation from a low voltage battery supply. Thus providing an ideal
Starter Project
for
beginners and a useful item of “test equipment” for any reader.
Copyright © 1999 Wimborne Publishing Ltd and
Maxfield & Montrose Interactive Inc
EPE Online, June 1999 - www.epemag.com - 573
&/,33,1* 9,'(2 )$'(5
A new series of periodic articles in which we present
a variety of simple-to-build and use projects
especially suited for construction by those who are
comparatively new to electronics and wish to build
interesting, inexpensive, and practical circuits that
do not require a great deal of expertise or test
equipment, and which are likely to work first time.
Experienced constructors will find these designs
useful as well
so it’s something for everyone, we
believe!
Many camcorders include a
video fader facility, but this is of-
ten in the form of a pushbutton
control with a fixed rate of fade. A
fader of this type is certainly us-
able, but offers no creative con-
trol to the user. The extremely
simple video fader describe here
has a conventional control knob
that offers precise control over
the fade characteristic.
The circuit provides what is
virtually a conventional fade to
black action, but the fading is pro-
vided by asymmetric clipping of
the picture modulation rather than
by attenuating it. This method of
fading operates in dif-
ferent manner to a
conventional fader,
and it produces a dif-
ferent effect on-
screen when the pic-
ture is faded.
E\ 52%(57 3(1)2/'
both types of fade are perfectly
usable. This project offers an
interesting alternative to a con-
ventional video fade effect, and
it costs very little to build.
The fader circuit is designed
for use with a standard UK PAL
composite video signal. It is
normally connected between
the video output of the cam-
corder and the video input of a
VCR, and is used when produc-
ing a tape of the best bits from
the raw footage in the cam-
corder. However, it can also be
connected between two VCRs
or any items of video equipment
that use the right form of video
signal. It is not suitable for use
with equipment that uses any
form of RGB signal, digital
video signal, or separate syn-
chronization signals.
tally faded out, albeit in a very
weak form. As the picture is
faded you see a weaker and
weaker version of it, but the pic-
ture is otherwise undistorted.
With the clipping method,
the brightest parts of the picture
are faded first, then the mid-
tones, and finally the darker ar-
eas. The picture collapses
rather than fades from the
screen.
The fact that this is an un-
conventional form of fading
does not mean that it is an infe-
rior effect. This really boils
down to a matter of taste, and
SYSTEM OPERATION
The waveforms of Fig.1
show how the clipping process
provides a fading action. In
somewhat simplified form,
these waveforms each repre-
sent two line scans. Each scan
starts with a negative synchro-
nization pulse followed by a
high frequency color burst sig-
nal. The rest of each line scan
is the color modulation, which is
of the positive variety for the
UK PAL system. In other words,
the stronger the signal voltage,
the brighter the screen at that
point in the line.
Waveform (a) shows the un-
processed composite video input
signal. In waveform (b) the clip-
ping process has just begun, and
the asymmetric clipping process
FADER TYPES
With a conven-
tional fader, the com-
plete modulation sig-
nal is still present
even when the picture
has been almost to-
Fig.1. Example waveforms as the signal
is progressively clipped.
Copyright © 1999 Wimborne Publishing Ltd and
Maxfield & Montrose Interactive Inc
EPE Online, June 1999 - www.epemag.com - 574

Plik z chomika:

Inne pliki z tego folderu:

Inne foldery tego chomika:

Zgłoś jeśli naruszono regulamin